john: but the u.s. department of health says a calorie is a calorie. >> it just hasn't been tested. one of the things we did when i started this organization. john: this being? >> the utritionist study. we went back to world war ii to every scientist that attempted to answer th question. we found 82 studies that have attempted to answer that. they were all probably the same limitations and problems. in 2012, there is plenty of anecdotal evidence. a calorie is not a calorie, necessarily. john: one thing that absolutely must be true if you should eat less fat. yet you eat lots of fat. and you're a doctor. a stanford doctr. what's that about? >> like i said, three or four years ago, when i got to the point where ms. chu overweight and my wife said i needed to be a little less not so thin, i realized that i probably had a carbohydra intolerance issues in all of whole grains and things that i was eating were probably leading to be becing fatter. and if i stripped that stuff out of my diet and i ate more fat, believe it or nt, all of the metabolic derangement that was underpinning my prop